1.5 kW质子交换膜燃料电池堆动态工况响应特性

考察了自制1.5 kW质子交换膜燃料电池(PEMFC)电堆在动态工况下的性能。研究了PEMFC电堆电压、功率、反应参数随车载工况运行出现的响应情况。发现在大电流密度下,由于各单电池的差异,电堆电压和功率出现比较明显的波动现象。在选定两个工况周期中,电堆各单电池电压的差异系数C_V最大达到4.23%,最高单电池电压和最低单电池电压相差0.106 V。数据分析表明在该动态工况下,PEMFC电堆的动态响应特性受到反应物和电堆温度变化、空气局部流量过大或不足以及电堆内部阳极和阴极出现明显压降等因素的影响。该研究不仅为后续耐久性测试提供分析依据,还对PEMFC电堆实际车载运行参数与控制策略的优化具有指导意义。     

PEMFC电堆动态工况响应性能试验

质子交换膜燃料电池（PEMFC）电堆动态响应特性对PEMFC电堆的耐久性和可靠性具有很大影响。本文试验考察了PEMFC电堆在动态工况下的输出性能、单电池电压均衡性变化和动态响应特性。结果表明,在整个动态运行工况下,电堆运行良好,进出口冷却液温差小于5℃。电流阶跃变化时电堆电压均衡性出现突增变化,同时随着电流的增大,稳态时电堆均衡性变差。在超负荷（200A）运行工况下,电堆各单电池之间输出差异变大,均衡性持续变差,电堆中间和前端单电池电压明显降低。此外,在整个动态响应过程中电流阶跃上升时的电压最大下冲值比电流阶跃下降时的电压最大上调量大,但输出电压能在10s内达到相对稳定的状态（电压波动率＜0.02）。通过该研究,以期为实际车载电堆运行和控制优化提供参考。     

大功率质子交换膜燃料电池电堆膜电极一致性研究

随着燃料电池应用领域的拓宽以及应用规模的不断扩大,大功率燃料电池电堆的需求也不断上升。大功率燃料电池电堆的电压一致性是衡量或影响电堆性能的重要指标。对某公司生产的65 kW大功率电堆进行了单电池一致性的研究,考察不同运行条件对于电堆一致性的影响,并对其产生的可能原因进行了深入的研究和讨论。研究结果表明：在额定功率和给定的运行条件下,电堆表现出了较好的一致性;电堆输出功率、电堆温度和温差、反应气体计量比、气体湿度等对电堆膜电极一致性均有较大的影响。其中输出功率、空气计量比、气体湿度对于电堆一致性的影响最为强烈,输出功率增高、空气计量比和空气湿度降低均会大幅度降低电堆的一致性。在研究结果的基础上,提出了保持大功率燃料电池电堆一致性的运行条件的建议。可为改善大功率电堆的设计和优化大功率电堆的运行条件,及促进我国燃料电池技术及产业的发展提供参考。     

氢气进气压力对空冷PEMFC性能的影响

空冷型质子交换膜燃料电池(PEMFC)具有自增湿、质量轻、系统操作简单等特点,适合应用于无人机等领域。氢气进气压力是影响空冷型PEMFC电堆性能的一个重要因素。以1 kW阴极开放式空冷型PEMFC电堆为研究对象,对比了不同氢气进气压力对单片电池电压及其一致性、电堆输出电压、输出功率以及氢气利用率的影响。研究结果表明,氢气进气压力越高,单片电池电压、电堆输出电压和功率越高,大电流下单片电池电压的一致性越好;此外,本实验利用排水法收集阳极尾气并计算氢气利用率,氢气进气压力越高,系统氢气利用率越低。     

1～5 kW高温聚合物电解质膜燃料电池堆的理论模拟与组装测试

以大尺寸单电池(有效工作面积为165 cm²)和多片单电池组装而成的电堆为研究对象，通过数值模拟和实验测试相结合的方法探究了单电池数量对高温聚合物电解质膜燃料电池堆输出性能、单池一致性和热管理的影响。模拟结果显示，当电堆的单池数量从10片增加至60片时，平均单池电压从0.6414 V略微降低至0.6404 V，且单池之间电压极差从1.8 mV增加至6.5 mV；单池间的平均工作温度从431.01 K升高至433.90 K，且每单池自身工作温度的极差从6.95 K增加至10.22 K。表明随着电堆单池数量的增加，电堆的平均单池电压呈轻微下降趋势，且单池间电压极差变大，单池电压一致性有所下降，单池间的温差变大，其单池自身的均温一致性也有所降低，电堆热管理难度增加。在模拟结果的指导下分别组装了30、60和120片单池的高温膜燃料电池堆，在氢/空干气、33 A的恒流放电条件下，测得30、60和120片单池电堆的平均单池电压分别为0.6566、0.6548和0.6552 V，单池极差从24 mV增加到59 mV，与模拟结果显示出良好的一致性，验证了模拟结果的有效性。在氢/空...     

质子交换膜燃料电池启动策略的实验研究

质子交换膜燃料电池(PEMFC)在启动时各单片电池将出现高电压,而高电压会加速催化剂碳载体的腐蚀,进而影响电堆的性能。为了降低燃料电池启动时形成的高电压和缩短高电压维持的时间,本文通过实验研究对比分析了常规启动、联合最低单片电压启动和减小氢气进气压力启动3种不同启动方式对PEMFC的影响,提出了一种新的PEMFC启动策略。该策略是减小电堆启动时氢气进气压力,当电堆最小单片电压值大于0.3V后立即切入10?启动负载。结果表明,该策略不仅可以明显降低电堆启动时最大单片电压值,还缩短了高电压维持的时间,有利于提高电堆耐久性,是一种十分有效的PEMFC启动控制策略。     

高温质子交换膜燃料电池性能衰减机理与缓解策略——第二部分： 操作条件

近些年高温质子交换膜燃料电池（HT-PEMFC）在稳态操作条件下的耐久性已经得到了巨大的改善，然而动态或异常操作条件仍严重影响了HT-PEMFC的寿命。针对该问题，本文概述了HT-PEMFC常见操作条件的特点，系统地总结了常见动态或异常操作条件下电池性能的衰减机理及其相应的缓解策略，并整理了该领域内报道的加速应力测试方案与寿命预测方法。最后本文对HT-PEMFC未来的发展进行了展望，随着HT-PEMFC商品化进程的推进，未来新型在线检测/诊断技术的开发、标准化测试方案与寿命预测模型的建立、电堆或系统结构的优化以及装配工艺与生产线的设计等很有可能成为该领域内的研究重点。     

带有蛇形流场的微生物燃料电池串联堆性能特性

以四个成功启动的带有蛇形流场的单电池构造了微生物燃料电池串联堆(MFCS-S),测试了MFCS-S性能,探讨了其性能提升的限制因素,研究了增加反极电池阴、阳极电解液流量,采取混联的方式运行,移除反极电池和反接反极电池对电堆性能的影响。实验结果表明:MFCS-S在输出电压为2.11 V时获得最大功率密度(2226 mW·m^-2);在一定电流条件下,性能较差的单电池发生电压反极,这是限制MFCS-S性能提高的主要原因;增加反极电池阴、阳极流量虽然不能较大幅度地改善单电池反极,但是却能大幅度提高电堆功率密度;采用混联方式运行不但可以有效避免电池反极,而且可以大幅度提高电堆功率密度;移除反极电池并不能有效地避免电池的反极,反接反极电池反而进一步加剧反极。     

全钒液流电池电堆的均一性

全钒液流电池电堆的均一性直接影响到其寿命。本文从流道结构、运行参数等方面,系统探讨了影响全钒液流电池电堆均一性的各种因素。通过优化管路结构和液流框结构,提高了电堆的均一性,随支管管径不断减小,当主管与支管管径由4∶3减小到4∶1时,电堆进液流量标准偏差由0.039m/s降到0.001m/s,电堆进液流速均一性得到改善;通过优化液流框结构,使电堆单体电池电解液流量标准偏差由0.142m/s降到0.032m/s,改善了电堆单体电池均一性。电解液流量、充放电电流密度等运行参数影响全钒液流电池电堆均一性,对其进行了实验与分析,结果表明:电堆电压标准偏差随充放电电流增大而线性增大,其斜率与截距均与电解液性质、电极材料性质及表面结构等因素有关;电堆电压标准偏差随电解液流速的增大而减小,且在超过一定流量后不再变化,为全钒液流电池材料选型优化、结构优化及运行提供技术支撑。     

聚醚砜-聚乙烯吡咯烷酮高温聚合物电解质膜及燃料电池堆性能研究

基于磷酸掺杂聚苯并咪唑膜（PA/PBI）的高温聚合物电解质膜燃料电池具有高的输出功率和优异的稳定性,然而PBI膜昂贵的价格和复杂的制备工艺限制了高温聚合物电解质膜燃料电池的商业化应用。本研究以成本低和制备工艺简单的聚醚砜-聚乙烯吡咯烷酮（PES-PVP）膜的商业化应用为目标,小规模制备了幅宽为40 cm的PES-PVP复合膜,证实了流延法放大制备PES-PVP复合膜的可行性。PES-PVP膜中每个PVP重复单元的吸附量达4.9个磷酸（PA）分子,且在180℃的质子电导率达85 mS·cm^-1。此外,尺寸为165 cm²的PA/PES-PVP高温膜电极在150℃的输出功率达0.19 W·cm^-2@0.6 V,与同尺寸的商业化PA/PBI高温膜电极的输出功率相当,并在近3000 h的寿命测试中展示出良好的稳定性。最后,将PA/PES-PVP高温膜电极（单片有效面积200 cm²）组装高温膜燃料电池短堆,其中基于3片膜电极的短堆展现出良好的电堆启停稳定性;基于20片膜电极电堆的峰值功率达1.15 kW。以上结果表明所制备的PA/PES-PVP是一种性能优良、价格便宜的高温聚合物电解质膜材料,并且基于该膜材料组装的高温聚合物电解质膜电池和电堆性能优异。本研究工作为高温聚合物电解质膜燃料电池关键材料和电堆的国产化提供了研究基础。     

Durability of ABPBI‐based MEAs for High Temperature PEMFCs at Different Operating Conditions

High temperature PEMFCs based on phosphoric acid‐doped ABPBI membranes have been prepared and characterised. At 160 °C and ambient pressure fuel cell power densities of 300 mW cm^–2 (with hydrogen and air as reactants) and 180 mW cm^–2 (with simulated diesel reformate/air) have been achieved. The durability of these membrane electrode assemblies (MEAs) in the hydrogen/air mode of operation at different working conditions has been measured electrochemically and has been correlated to the cell resistivity, the phosphoric acid loss rate and the catalyst particle size. Under stationary conditions, a voltage loss of only –25 μV h^–1 at a current density of 200 mA cm^–2 has been deduced from a 1,000 h test. Under dynamic load changes or during start–stop cycling the degradation rate was significantly higher. Leaching of phosphoric acid from the cell was found to be very small and is not the main reason for the performance loss. Instead an important increase in the catalyst particle size was observed to occur during two long‐term experiments. At high gas flows of hydrogen and air ABPBI‐based MEAs can be operated at temperatures below 100 °C for several hours without a significant irreversible loss of cell performance and with only very little acid leaching.     

Design,Fabrication and Preliminary Study of a Mini Power Source with a Planar Six‐cell PEM Unitised Regenerative Fuel Cell Stack

A novel micro planar fuel cell power supplier, in which a six‐cell PEM unitised regenerative fuel cell (URFC) stack is used as the power generator, was designed and fabricated. Six membrane electrode assemblies were prepared and integrated on one piece of membrane by spraying catalyst slurry on both sides of the membrane. Each cell was made by sandwiching a membrane electrode assembly (MEA) between two graphite monopolar plates and six cell units were mechanically fixed in two organic glass endplates. When the stack was operated in an electrolysis mode, hydrogen was generated from the splitting of water and stored using a hydrogen storage alloy; conversely, when the stack was operated in fuel cell mode, hydrogen was supplied by the hydrogen storage alloy and oxygen was supplied from air by self‐breathing of the cathode. At room temperature and standard atmospheric pressure, the open‐circuit voltage (OCV) of the system reached 4.9 V, the system could be discharged at a constant current density of 20 mA cm^–2 for about 40 min, and the work voltage was ∼2.9 V. The system showed good stability for 10 charge–discharge cycles.     

Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little contribution of the membrane degradation to the performance losses during the potential cycling tests. As the major mechanism of the fuel cell performance degradation, the electrochemical active area of the cathodic catalysts showed a steady decrease in the cyclic voltammetric measurements, which was also confirmed by the post TEM and XRD analysis. A strong dependence of the fuel cell performance degradation on the catalyst supports was observed. Graphitization of the carbon blacks improved the stability and catalyst durability though at the expense of a significant decrease in the specific surface area. Multi‐walled carbon nanotubes as catalyst supports showed further significant improvement in the catalyst and fuel cell durability.     

Effect of calixpyrrole on electrochemical properties of Pt electrocatalyst in phosphoric acid electrolyte

In high-temperature proton exchange membrane fuel cells and phosphoric acid fuel cells, concentrated phosphoric acid is used as a proton-conducting medium. However, the use of phosphoric acid causes an adsorption problem onto Pt catalyst, which is known to impede the oxygen reduction reaction. To solve the problem, calixpyrrole is introduced as an electrode additive to block the adsorption of phosphate ion onto Pt catalyst. The introduction of calixpyrrole which can strongly interact with phosphate ion results in the enlargement of the available surface area of Pt catalyst and, accordingly, the enhancement of catalyst utilization in electrode. Among calix[n]pyrrole class, calix[4]pyrrole is synthesized and used as the electrode additive in this study.     

高温质子交换膜燃料电池性能衰减机理与缓解策略——第一部分：关键材料

高温质子交换膜燃料电池（HT-PEMFC）具有耐CO毒化能力强、水热管理简单、能量利用率高等优点,但同时高温酸性环境也使其面临着耐久性不足的问题。针对该问题,本文分别概述了HT-PEMFC中质子交换膜、气体扩散电极、双极板以及密封件等四种电池组件的常用材料的物理化学特性,并系统地总结了近些年关于HT-PEMFC各组件性能衰减过程的机理、危害、影响因素以及相应缓解策略的研究进展。最后对HT-PEMFC未来的发展进行了展望,其中开发高强度轻薄双极板和高耐久性密封件、优化电堆成本以及探索新型电解质膜体系等研究方向有望成为未来该领域内的研究重点。     

Effect of Compression Cycling on Polybenzimidazole‐based High‐Temperature Polymer Electrolyte Membrane Fuel Cells

Contact pressure cycling experiments have been conducted with various commercial high temperature PEM membrane‐electrode‐assemblies based on phosphoric acid doped PBI. Two different membrane‐electrode‐assembly types have been electrochemically investigated employing linear sweep voltammetry, electrochemical impedance spectroscopy and polarization curves, but also micro‐computed tomography imaging has been used as post‐mortem investigation technique. Thickness displacement changes on the membrane‐electrode‐assemblies (MEA) during the experiences have also been recorded. Reversible and irreversible effects have been observed in MEA behavior during the three contact pressure cycles. Furthermore, the micro‐computed tomography tool allows a detailed visual insight into the structural effects of compression forces on the MEA. The electrochemical characterization has revealed that damages under contact pressure cycling have been induced in both kinds of MEAs. Moreover, once MEA damages have appeared, they are facilitated from cycle to cycle. These damages are related to hydrogen crossover and short circuit formation that develop fuel cell performance deterioration. Thus, micro‐computed tomography imaging investigations reveal defects, pin holes or cracks within the catalyst layer and membrane e.g., which may cause degradation aspects like hydrogen crossover or loss of electrical isolation already observed by the electrochemical characterization.     

液相进样直接甲醇燃料电池性能研究

报道了用研制的Pt-Ru/C催化剂, 采用特殊工艺制备了膜电极, 并组装了直接甲醇质子交换膜单电池系统。考察了电极扩散层制备方法、催化剂层中催化剂、Teflon-C以及Nafion液的用量等电极制备工艺条件以及空气作为氧化剂对单电池性能的影响。结果表明：采用刷涂法制备电极扩散层比喷涂法好,催化剂层中催化剂的优化含量为0.6mg·cm-2,Teflon-C、Nafion液的最佳用量分别为0.3 mg·cm-2、0.5 mg·cm-2。当工作温度为80℃时,输出电压为0.3V,氧气作为阴极气体的输出电流密度为36mA·cm-2;而空气作为阴极气体的输出电流密度为22.5mA·cm-2。膜电极有效面积为9cm2的的液相进样直接甲醇/氧气燃料电池三电池电堆的最大功率为0.285W,此时输出电压为0.7V,输出电流为0.407A;而液相进样直接甲醇/空气三电池电堆的输出电压为0.635V,输出电流为0.252A时,最大功率为0.160W。     

On a new degradation mode for high-temperature polymer electrolyte fuel cells: How bipolar plate degradation affects cell performance

The contribution of the bipolar plate material to the overall degradation of a high temperature membrane electrode assembly (HT MEA) for polymer electrolyte fuel cells (PEFCs) is studied in terms of performance decrease, phosphoric acid uptake in the bipolar plates and change of surface morphology of the bipolar plates. Two different high temperature graphite composites, a surface treated graphite and a gold coated stainless steel flowfield and the respective MEAs are compared after operation at 180 °C. Both graphite surface treatment and gold coating lead to negligible uptake of the electrolyte and ensure low degradation rates, whereas the composite plates exhibit high uptake of acid from the MEA into the surface near bulk. Apparent MEA degradation caused by acid redistribution from the MEA to the increasingly porous plates is observed in terms of increased ohmic cell resistances and reduction of catalyst utilization as consequence of acid loss from the catalyst layers.     

An isothermal model of a laboratory intermediate temperature fuel cell using PBI doped phosphoric acid membranes

A two-dimensional isothermal model is described for an intermediate temperature fuel cell using a phosphoric acid doped polybenzimidazole (PBI) membrane. The model considered the membrane-electrode-assembly and gas flow channels. All the major transport phenomena were taken into account except the cross-over of species through the membrane. The catalyst layers were treated as spherical catalyst agglomerates with porous inter-agglomerate spaces. The inter-agglomerate spaces are filled with a mixture of electrolyte (hot phosphoric acid) and polytetrafluoroethylene (PTFE). The model was validated against experimental data and used to study the influence of the catalyst layer properties on performance. Through the analyses of the effectiveness factor the model showed that utilisation of catalyst particles was very low at high current densities. At these conditions, the reaction occurs mainly on the surface of the agglomerate. An optimum phosphoric acid loading was found from the model simulations. The model was also used to demonstrate the resistance of the intermediate temperature fuel cell to anode poisoning by CO.